Chapter 24An Introduction to Organic Chemistry

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Chapter 24 An Introduction to Organic Chemistry
24.1 What are organic compounds?
24.2 Introducing organic chemistry
24.3 Organic molecules represented by structural
formulae
24.4 Saturated and unsaturated hydrocarbons
24.5 Classification of organic compounds
24.6 Naming of organic compounds
24.7 Structural formulae from IUPAC names
CONTENTS OF CHAPTER 24
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24.1 WHAT ARE ORGANIC COMPOUNDS?
Figure 24.2 A collection of substances
containing organic compounds.
24.1 WHAT ARE ORGANIC COMPOUNDS?
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ORGANIC COMPOUNDS are carbon compounds.
A24.1
CO, CO2, Na2CO3, KHCO3, H2O, NH3, KOH, HCl, HNO3,
NaCl. (Other answers may be given.)
24.1 WHAT ARE ORGANIC COMPOUNDS?
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24.2 INTRODUCING ORGANIC CHEMISTRY WHAT IS
ORGANIC CHEMISTRY?
ORGANIC CHEMISTRY is a branch of chemistry
focusing on carbon compounds.
24.2 INTRODUCING ORGANIC CHEMISTRY
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Figure 24.3 Organic chemistry is often
studied as a separate branch of chemistry.
24.2 INTRODUCING ORGANIC CHEMISTRY
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GENERAL CHARACTERISTICS OF ORGANIC
COMPOUNDS Constituent elements and bonding in
organic compounds Almost all organic compounds
contain hydrogen besides carbon. Most organic
compounds are covalent compounds. Some consist of
simple molecules. Others consist of very large
molecules (macromolecules).
24.2 INTRODUCING ORGANIC CHEMISTRY
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Figure 24.4 Most organic compounds consist of
molecules (a) Hexane consists of simple
molecules. (b) Starch consists of
macromolecules.
24.2 INTRODUCING ORGANIC CHEMISTRY
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A24.2
Tetrachloromethane CCl4. (Other answers may be
given.)
Reactions of organic compounds In general,
reactions involving organic compounds have the
following in common
? The reactions are usually slow (when compared
with common inorganic reactions). ? In most
cases, organic compounds can burn to give carbon
dioxide and water.
24.2 INTRODUCING ORGANIC CHEMISTRY
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Figure 24.5 Ethanol, an organic compound, burns
to form carbon dioxide and water.
24.2 INTRODUCING ORGANIC CHEMISTRY
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UNIQUENESS OF CARBON Carbon has the unique
property of forming a very large number of
compounds (over 4 000 000). There are three
reasons for this
(1) Carbon atoms can form strong single, double
and triple covalent bonds with other carbon
atoms. (2) Each carbon atom can form four single
covalent bonds. (3) Carbon can form strong bonds
with other elements.
24.2 INTRODUCING ORGANIC CHEMISTRY
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24.2 INTRODUCING ORGANIC CHEMISTRY
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24.3 ORGANIC MOLECULES REPRESENTED BY
STRUCTURAL FORMULAE
Table 24.1 Structures of a butane molecule and a
2-methylpropane molecule, as represented by
formulae and models.
24.3 ORGANIC MOLECULES REPRESENTED BY
STRUCTURAL FORMULAE
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Table 24.2 Structural formulae and models of
some organic compounds.
24.3 ORGANIC MOLECULES REPRESENTED BY
STRUCTURAL FORMULAE
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A24.3
24.3 ORGANIC MOLECULES REPRESENTED BY
STRUCTURAL FORMULAE
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24.4 SATURATED AND UNSATURATED HYDROCARBONS Hyd
rocarbons may be saturated or unsaturated.
Hydrocarbons containing only single bonds are
said to be saturated. Those containing one or
more carbon-carbon multiple bonds (C C, C ?
C) are unsaturated. For example,
24.4 SATURATED AND UNSATURATED HYDROCARBONS
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24.5 CLASSIFICATION OF ORGANIC
COMPOUNDS FUNCTIONAL GROUP
Figure 24.7 Structural formulae and models of
butane, but-1-ene and butan-1-ol.
24.5 CLASSIFICATION OF ORGANIC COMPOUNDS
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A FUNCTIONAL GROUP is an atom or group of atoms
responsible for most of the chemical properties
of a compound.
A24.4
(a) Yes. They have the same functional group
(OH). (b) A lt B lt C lt D in boiling point. Van
der Waals forces are greater between larger
molecules.
HOMOLOGOUS SERIES
The hydrocarbons methane, ethane, propane and
butane belong to the same homologous series the
alkane series.
24.5 CLASSIFICATION OF ORGANIC COMPOUNDS
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Table 24.3 Names, formulae and models of the
four hydrocarbons present in natural gas.
24.5 CLASSIFICATION OF ORGANIC COMPOUNDS
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A HOMOLOGOUS SERIES is a family of compounds all
having the same general formula and with adjacent
members differing by a CH2 unit. The
individual members of a homologous series are
referred to as HOMOLOGUES.
A24.5
(a) Put n 5 in CnH2n2. The molecular formula
is C5H12. (b) Put n 11 in CnH2n2. The
molecular formula is C11H24.
24.5 CLASSIFICATION OF ORGANIC COMPOUNDS
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Another homologous series is the alkanol
(alcohol) series, with the general formula
CnH2n1OH.
Figure 24.8 Methanol and ethanol are the first
two members of the alkanol series.
24.5 CLASSIFICATION OF ORGANIC COMPOUNDS
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24.5 CLASSIFICATION OF ORGANIC COMPOUNDS
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Table 24.4 Some common functional groups and
homologous series, with the first member in each
series shown.
24.5 CLASSIFICATION OF ORGANIC COMPOUNDS
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A24.6
24.5 CLASSIFICATION OF ORGANIC COMPOUNDS
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24.6 NAMING OF ORGANIC COMPOUNDS NAMING
ALKANES BY THE IUPAC SYSTEM Naming
straight-chain alkanes All alkanes have names
ending with the suffix -ane.
24.6 NAMING OF ORGANIC COMPOUNDS
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Table 24.5 Structural formulae and names of
the 10 simplest straight-chain alkanes.
24.6 NAMING OF ORGANIC COMPOUNDS
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Alkyl groups Alkyl groups are derived from
alkanes by the removal of a hydrogen atom. They
are often represented by the symbol R.
Table 24.6 Some alkyl groups and their
parent alkanes.
24.6 NAMING OF ORGANIC COMPOUNDS
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A24.7
(a) (i) Hexyl (ii) Octyl (b) (i) CH3(CH2)3CH2 (
ii) CH3(CH2)5CH2
Naming branched-chain alkanes The IUPAC name for
a branched-chain alkane consists of 2 parts
(1) The prefixes which indicate the alkyl group
substituents (2) The root which indicates the
parent alkane (the main carbon chain).
24.6 NAMING OF ORGANIC COMPOUNDS
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That is, Prefixes Root
(alkyl groups) (main carbon chain) The basic
IUPAC rules of naming can be illustrated by the
example below
24.6 NAMING OF ORGANIC COMPOUNDS
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The name of the compound is
A24.8
(a) 2,3-dimethylbutane (b) 4-ethyl-3-methylheptane
24.6 NAMING OF ORGANIC COMPOUNDS
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NAMING HALOGEN-SUBSTITUTED ALKANES
A24.9
2-bromo-1-iodo-3-methylpentane
NAMING ALKENES Alkenes have the general formula
CnH2n. We can name them with the same general
rules for alkanes, but using the suffix -ene
instead of -ane.
24.6 NAMING OF ORGANIC COMPOUNDS
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For example,
24.6 NAMING OF ORGANIC COMPOUNDS
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24.6 NAMING OF ORGANIC COMPOUNDS
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A24.10
(a) 2-methylbut-2-ene (b) chloroethene
24.6 NAMING OF ORGANIC COMPOUNDS
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24.6 NAMING OF ORGANIC COMPOUNDS
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CH3 1CH32C3CH3 2-methylpropan-2-ol OH

A24.11
(a) Butan-1-ol (b) 4-chlorobutan-2-ol (not
1-chlorobutan-3-ol)
24.6 NAMING OF ORGANIC COMPOUNDS
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NAMING ALKANOIC ACIDS Alkanoic acids have the
general formula CnH2n1COOH or R COOH, where
R is an alkyl group or hydrogen. Names of
some alkanoic acids are given below HCOOH
(methaneoic acid) methanoic acid CH3COOH
ethanoic acid CH3CH2COOH propanoic
acid CH3CH2CH2COOH butanoic acid 3
2 1 CH3CHCOOH 2-methylpropanoic acid CH3
24.6 NAMING OF ORGANIC COMPOUNDS
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A24.12
3-chlorobutanoic acid.
24.6 NAMING OF ORGANIC COMPOUNDS
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24.7 STRUCTURAL FORMULAE FROM IUPAC NAMES
24.7 STRUCTURAL FORMULAE FROM IUPAC NAMES
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24.7 STRUCTURAL FORMULAE FROM IUPAC NAMES
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A24.13
24.7 STRUCTURAL FORMULAE FROM IUPAC NAMES
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A model of butane.
24.7 STRUCTURAL FORMULAE FROM IUPAC NAMES
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A model of but-1-ene.
24.7 STRUCTURAL FORMULAE FROM IUPAC NAMES
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A model of butan-1-ol.
24.7 STRUCTURAL FORMULAE FROM IUPAC NAMES
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A model of butanoic acid.
24.7 STRUCTURAL FORMULAE FROM IUPAC NAMES
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SUMMARY
1. Organic compounds are carbon compounds. 2.
Almost all organic compounds contain hydrogen
besides carbon. Many contain oxygen too. They are
usually covalent compounds. 3. In general,
reactions involving organic compounds are slow.
In most cases, organic compounds can burn to give
carbon dioxide and water.
SUMMARY
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4. Carbon forms a very large number of organic
compounds because
? carbon can form strong bonds with itself and
with other elements ? each carbon atom can form 4
single covalent bonds
5. Saturated hydrocarbons are compounds (with
carbon and hydrogen only) containing only single
bonds. Unsaturated hydrocarbons are compounds
(with carbon and hydrogen only) containing one or
more carbon-carbon multiple bonds (CC or
C?C). 6. A functional group is an atom or group
of atoms responsible for most of the chemical
properties of a compound.
SUMMARY
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7. A homologous series is a family of compounds
having the same general formula with adjacent
members differing by a CH2 unit. See Table
24.4 on p. 29. 8. Organic compounds are usually
named by the IUPAC system of naming. For rules
and examples, refer to pp. 30 37.
SUMMARY